Caterpillar Inc.

Donald H Sherman

William K Engel

Michael C Long

Michael H Haselkorn

Michael H Hinrichsen

Robert J Huebner

Kenneth R Watts

James C Goade

Howard Savage

Guy C Carlson, Jr

A method is provided for producing a piston assembly adapted for use in a hydraulic pump or motor and having an overall length shorter than previously known piston assemblies while maintaining a strong mechanical connection and a high, efficient volumetric output. The method includes the steps of forming a slipper with a spherical ball on one end; forming a piston having a body portion and a connecting portion, the connecting portion having a spherical bottom surface, a groove spaced from the bottom surface and a contoured portion having an angled outer surface and an inner surface; inserting the spherical ball into the cavity; forcing the contoured portion inwardly to place the inner surface into contact with the spherical ball and to substantially longitudinally align the outer surface of the piston body with the angled surface of the contoured portion; heat treating the piston to a predetermined hardness and depth; and finishing the total longitudinal length of the piston to a finished size.

Method of producing a piston assembly

A cylinder barrel includes a casting having a plurality of ceramic bore liners cast in situ within the casting. The cylinder barrel is made by positioning the ceramic bore liners at predetermined locations within a casting mold and pouring a molten ferrous metal into the mold so as to envelope the bore liners.

Method of making a cylinder barrel having ceramic bore liners

Piston assemblies for use in fluid translating devices normally are made of hardened metal alloy materials which require very smooth surface and are always subject to varying degrees of thermal expansion when being operated at high operating temperatures. In the subject arrangement, a piston assembly is provided and is constructed of most, if not all, ceramic components. The piston assembly includes a ceramic piston having a spherical head portion at one end thereof which rests in a spherical cavity of a ceramic slipper and held therein by a cylindrical ring. The cylindrical ring can be of a one-piece or a two-piece design which is in contact with the spherical head portion and bonded to the ceramic slipper, thus, retaining the spherical head portion. The cylindrical ring could also be made of a metallic material. The metallic ring is bonded to the ceramic slipper and subsequently swaged to hold the spherical head portion within the spherical cavity. The subject ceramic piston assembly provides a very smooth surface which reduces sliding friction and likewise the effects of thermal expansion and inertia are minimized by the use of a ceramic material. Consequently, the subject piston assembly is very efficient when operating at high temperatures and, likewise, is easy to manufacture and assemble.

Piston assembly for a fluid translating device

Axial piston fluid translating units commonly experience undesirable shaft deflections and barrel tilting during operation. A fluid translating unit includes a barrel plate interposed the end of a barrel and a porting surface defined within a housing thereof. The barrel plate is axially spaced from an end of the barrel and is in face sealing engagement with the porting surface. The barrel plate defines a plurality of fluid ports, each communicating between one of a plurality of barrel cylinder bores and the porting surface. In one aspect a plurality of counterbores are provided in the barrel in surrounding relation to the fluid ports. A plurality of seal rings having a sealing end defining an annular seal face of a predetermined width for face sealing engagement with the barrel plate. The seal rings are each disposed in one of the counterbores in circumferential sealing relation of a predetermined length which is no greater than the width of the sealing face. A plurality of annular springs are disposed in the counterbores for urging the seal rings into sealing engagement with the other of the barrel and the barrel plate. This arrangement permits tilting of the barrel without damaging contact or excessive leakage between the barrel plate and the porting surface.

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Morton, IL, United States of America

Donald H Sherman